The Null Material for OctaneRender® is used for mesh objects that have an invisible surface but contain a medium. This is equivalent to setting up a specular material with IOR 1 and a reflection of 0 and a transmission of 1. However, that methodology is no longer needed given Nested Dielectric support. The Null Material was created to make a medium with no surface work in all cases.


null material render


In the example above, the same object is assigned two separate null materials with a Volume Medium applied; the object on the left has a density of 50, while the object on the right has a density of 500. The object is the Nefertiti bust from the Cinema 4D Asset Browser repository.


null material attributes


Null Material Parameters

Basic properties tab


Enabled — Enables the material.

Transmission — Enables the Transmission aspects of the material.

Geometry — Enables the Geometry aspects of the material.

Transmission properties tab


Medium — Add any medium node.

Opacity — Controls the transparency of the material (from 0..1) or via a grey scale texture.

Affect Alpha — If enabled, refractions will affect the alpha channel.

Geometry properties tab


Displacement — Accepts any displacement node to create highly detailed geometry with a low memory footprint.

Smooth — If disabled, normal interpolation will be disabled and triangle meshes will appear facetted.

Smooth Shadow Terminator — If enabled, self-intersecting shadows are smoothed according to the polygon's curvature.

Round Edges — Rounds the geometry edges by using a shading effect, rather than creating additional geometry. See Round Edges for more information.

Priority — Used to resolve the ambiguity in overlapping surfaces, the surface priority control allows artists to control the order of preference for surfaces. A higher number suggests a higher priority for the surface material, which means it is preferred over a lower priority surface material if a ray enters a higher priority surface and then intersects a lower priority surface while inside the higher priority surface medium.